1. Field of the Invention
This invention relates to a center pivot irrigation system having the ability to irrigate the corners of the field being irrigated. More particularly, this invention relates to an improved means for guiding the movement of the corner span with respect to the center pivot portion of the system which includes an ultra wide band (UWB) guidance system.
2. Description of the Related Art
Conventional center pivot irrigation systems comprise an elongated main boom pivotally connected at its inner end to a center pivot structure and extending outwardly therefrom. The main boom of the conventional center pivot irrigation system is comprised of a plurality of pipes connected together in an end-to-end fashion which are supported upon a plurality of drive towers. In most conventional center pivot irrigation systems, the outermost drive tower is the master tower with the other drive towers being selectively driven in response to angular displacement of the boom section adjacent thereto.
In the early 1970s, corner systems for center pivot irrigation systems were developed to enable the corners of a square field to be irrigated. See, for example, U.S. Pat. Nos. 3,797,517 and 3,902,668.
Although the prior art systems do perform generally satisfactorily to drive and steer the extension booms, it is believed that the instant invention, utilizing an ultra wide band (UWB) guidance system, is more reliable and is more accurate than the prior art systems.
A self-propelled irrigation system is disclosed which includes an elongated main boom pivoted at one end to a center pivot apparatus which is supported on a plurality of self-propelled, non-steerable drive towers, with an extension boom (corner span) pivotally secured to the other end of the main boom for irrigating corner areas of the field. A steerable drive tower supports the extension boom and includes a pair of steerable wheels. A steering means is provided for steering the steerable drive wheels for guiding the steerable drive tower along a preselected path, thereby causing the pivotal extension of the extension boom into the corner areas of the field as the main boom approaches the same and pivotal retraction of the extension boom out of the corner areas of the field as the main boom departs the same. A control means is provided for controlling the steering of the drive wheels of the steerable drive tower. The control means includes an ultra wide band (UWB) receiver and a computer means for receiving and processing UWB information as to the location of the steerable drive tower and for determining the optimal steer angle for the steerable drive wheels relative to the movement of the main boom for positioning the steerable drive wheels in the optimal steer angle. The UWB receiver and computer are positioned on the steerable drive tower. One or more UWB transmitters are located within receiving range of the UWB receiver. Signals transmitted by the UWB transmitters are received by the UWB receiver on the steerable drive tower and are used to determine current position and optimal steer angle relative to the main boom.
Therefore, it is a principal object of the invention to provide a corner irrigation system including an UWB guidance system.
A further object of the invention is to provide a corner irrigation system including an UWB receiver means and a computer means for receiving and processing UWB information as to the location of the main boom and for determining the optimum steer angle for the steerable drive wheels of the extension boom for the current position of the main boom and for positioning the steerable drive wheels in the optimal steer angle.
A further object of the invention is to provide a system of the type described which utilizes an UWB guidance means to accurately position the extension boom with respect to the main boom.
These and other objects will be apparent to those skilled in the art.